1. Field of the Invention
The present invention pertains to the art of appliances and, more particularly, to a latching mechanism for the door of an appliance.
2. Discussion of the Prior Art
The desire to latch an access door of an appliance in a closed position for various reasons is recognized in the art. Particularly, it is often desired to assure the positive latching of an appliance door during certain operating modes for safety reasons, as well as to enable the appliance to operate properly. For instance, the need for an access door latching arrangement is particularly realized in dishwashing machines. That is, as the machine proceeds through a washing operation, there is a need to maintain a proper seal about the periphery of the access door in order to assure that water, which is sprayed throughout the interior of the dishwasher in various stages of an overall washing operation, does not leak about the access door. Therefore, although a sealing gasket may be provided about the access door, it is necessary to maintain the door in a proper position and to latch the door to maintain the desired sealing.
Of course, the need to incorporate a latching mechanism in an appliance adds to the associated manufacturing costs. In addition, the latching mechanism can introduce certain design constraints and considerations. For example, given the life expectancy of a typical household appliance, the latching mechanism must be effectively designed for reliable operation over a prolonged period of time. Therefore, the mechanism must accommodate manufacturing tolerances and possible relative shifting between the access door and the remainder of the appliance over its useful life in order to avoid the need for independent adjusting of the latching mechanism for proper operation.
In latching mechanisms for certain appliances, it has heretofore been proposed to electrically signal when a latched condition has been reached, with the signal being received by a control unit which regulates other stages of operation for the appliance. For example, as indicated above, it would not be desirable to initiate a dishwashing operation until it was assured that the access door for the dishwasher was fully latched. However, when utilizing an electrical switch in connection with the latching mechanism for an appliance, there can arise certain timing considerations. That is, it would be beneficial to assure that an appropriate electrical signal is forwarded to the controls for the dishwasher upon an initial stage of unlatching of the appliance door rather than simultaneously with the reaching of an unlatched condition. In any event, although various latching mechanisms for dishwashers and other appliances have already been proposed in the art, in general, these known arrangements are considered to have certain shortcomings such that a need exists in the art for an improved mechanism for reliably latching the access door of an appliance, as well as providing for an improved timing arrangement when electrically signaling the latching status of the mechanism to a control unit of the appliance.
The present invention is directed to a mechanism particularly adapted for use in latching a pivotal access door of an appliance in a closed position during predetermined modes of operation of the appliance. The latching mechanism incorporates structure for releasably retaining the door in a closed position, as well as additional structure for electrically signaling the latching state of the mechanism to a control unit of the appliance in a timed manner.
In accordance with a preferred embodiment of the invention, the latching mechanism includes a latch housing within which is rotatably mounted a catch member. The catch member is actually rotatably supported between latching and unlatching positions upon a latch bracket or carrier which, in turn, is pivotably supported in the latch housing. The carrier is biased, preferably by a pair of laterally spaced springs, into engagement with a cam pin or rod which acts as a pivot stop for the carrier. In accordance with a first embodiment of the invention, a cross pin is connected to the carrier and rotatably supports a latch handle having one end portion which is adapted to engage the carrier for rotating the same against the biasing force of the springs. The cross pin actually extends through a pair of laterally spaced slots formed in the latch housing such that terminal ends of the cross pin are exposed. Electronic switches are arranged adjacent the terminal ends of the cross pin and are adapted to be depressed when the latching mechanism assumes a latched condition. A spring is also provided to bias the handle towards a non-engagement position with the carrier.
The catch member itself is formed with a camming surface defining at least first and second radially spaced detent positions adapted to be engaged by the cam pin depending upon whether the latching mechanism is in a latched or unlatched state. More specifically, when the overall latching mechanism is in an unlatched state, the catch member is located in a position wherein the carrier is depressed and the cam pin is received in the first detent in order to maintain the catch member in a desired receiving position for a latch striker. That is, the catch member includes first and second spaced arms that define a receiving area therebetween which is aligned with an opening provided in a rear portion of the latch housing for receiving the latch striker. In this unlatched condition, the carrier is spring loaded and the cross pin is shifted to a position wherein the electric switches are not engaged. When the latch striker enters between the arms of the catch member, the catch member is forced to rotate which causes the cam pin to come out of engagement with the first detent, ride along the camming surface and become positioned at the second, latching detent. In the latching position, the carrier is shifted relative to the housing and, in turn, the cross pin is shifted within the receiving slots of the housing to engage the electrical switches. With the switches engaged, a signal is provided to verify that the mechanism is properly latched.
In a second preferred embodiment of the invention, the latch handle is replaced by a shortened handle which, instead of pivoting about an axis defined by the cross pin, it is rotatably supported directly by the latch housing. In this embodiment, the handle is provided with two projecting prongs which directly abut the carrier for pivoting of the carrier and shifting of the cross pin against the biasing force of the latch springs. This second embodiment also has a modified form wherein the handle is completely removed. In this modified form, the latching mechanism is shifted from an unlatched condition to a latched condition by simply pushing on the appliance door such that the latch striker causes the catch member to automatically rotate. In order to unlatch the overall assembly, the appliance door is pulled by a force which causes the carrier to deflect against the biasing force of the springs, with a corresponding rotation of the catch member. In each of the embodiments, the carrier is rotated about an axis defined by a reinforcing rib of the housing to cause the cross pin to activate the electronic switches. Mounting the cross pin in slots enables an appropriate timing between the signals sent from the switches to a control unit of the appliance and the actual latching state change of the overall mechanism.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of the preferred embodiments thereof, when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.